The mouthpiece of a single-reed woodwind instrument is a device upon which the vibrating reed element is normally mounted to a surface of the mouthpiece, so that the tapered, less-thick end of the reed, being very flexible, functions as a reed valve. In order to produce proper tones of a single-reed woodwind instrument, a player must master several techniques (referred to as embouchure). One of the techniques is to position the mouthpiece in a player's mouth. Often times, this has been very difficult to master especially for a novice player to learn because the depth of mouthpiece into the player's mouth cannot be easily controlled or detected. This problem leads many frustrations for both teachers and students of single-reed woodwind instruments. Therefore, it would be desirable to have an apparatus that can alleviate the aforementioned problem.